Has anyone here ever had trouble with the Dot 5 brake fluid used in the pre 2004/5 Dynas? Silicone based fluid is well known to to cause brake fade when it gets hot. I've not had my Dyna through a summer of long rides yet so just wondered. If there's a problem I'll sort it while I'm doing the winter work.

Cheers
Derv

 

Derv, I haven't experienced this problem but wanted to let you know that the new (March) issue of American Rider has a tech article about brake fluids.

 

Whereas DOT 3 is susceptible to water/humidity contamination. Dot 5 is susceptible to air contamination, that is very minute bubbles stay suspended in the fluid, as the fluid heats up the bubbles expand, but DOT 5 is not as dangerous to painted surfaces as DOT 3. I change out my DOT 5 every 2 years. It will change color from purple to amber as it ages. Hope this helps.

 

Haven't had any problems on my 01.

 

I would take DOT 5 any day over 3 or 4. I had an 04 E-glide that had it and I had no problems. I did make the switch to speed bleeders though. If it gets on your paint you just wipe it off right away and you are good to go.

 

Not a Dyna, but my RK has gotten moisture mixed in the fluid (DOT5) in the master cylinder (tropical climate). This corrodes the plunger, which will affect the brake pull with temperature change. Mushy when hot, firm when cold. Either replace with a master cylinder rebuild kit or clean the plunger fixes the problem. Either way, you need to take it apart and flush the system. Had this happen on the front master cylinder (Twice) in 10 years. No problems otherwise and no issues with the rear brakes and Hydraulic clutch, which use DOT5 as well. Checking the seal and regularly replacing fluid is a good practice.

 

Personally I like DoT 4 better than 5. Just seems to keep a firmer feel longer. That being said, I haven't had any problems with DoT 5 in my old Road King or my FXD. Change it every 18 months - 2 years depending on condition.

 

Here is some additional info.

http://www.motorcycleproject.com/mot...rakefluid.html

 

Thanks for replies fellas, much appreciated. I didn't know Dot 5 was purple, I'm guessing it's what the guys on American Chopper use then? I also wasn't aware that it changed colour as it aged, the stuff that came out of mine was amber so I'm guessing it's over due a change anyway.

I only have to change it because I've put a longer line in to reach the new bars. Dot 5 isn't easy top get hold of here in the UK - I'd probably get it from HD but my nearest stealership is about 30 miles away - they double the price of everything here anyway! I tried several local motor parts suppliers but none had so I've ended up sending getting on the internet from an independent HD / custom biker parts place.

I'll stick with the Dot 5 for now but if it starts giving probs, I'll drain and flush the system, change the seals and go with Dot 4 or 5.1.

Thanks again for the replies

Derv